1. Field of the Invention
The present invention relates to a steering wheel assembly for vehicles such as automobiles and, more particularly, to a horn switch mechanism mounted on the steering wheel assembly.
2. Description of the Prior Art
The prior art horn switch mechanism on a steering wheel had to be made by troublesome steps, i.e., by mounting each of the component parts of the mechanism one after another on the steering wheel body, as disclosed in Japanese Utility Model Publication No. 58-4757. For this reason, an experimental switch-button pushing operation by the manufacturer had to be conducted after the completion of mounting of all of the component parts of the switch mechanism on the steering wheel body. If the switch was found to be defective, complicated and troublesome steps were required to remedy the defect with a resultant low yield of manufacture.
The prior art has another problem that the outer covering of a soft plastic material such as vinyl chloride or urethane molded on a metallic core of the steering wheel body tends to be thermally deformed. In the case where the horn switch mechanism is mounted in a recess or switch-receiving space formed in the plastic outer covering, as in many automotive steering wheels, if the thermal deformation of the plastic outer covering displaces the inner peripheral surface of the switch-receiving space inwardly due to thermal deformation of the covering, the horn switch button cannot be smoothly pushed to move a movable switch contact member into contact with a stationary switch contact member. On the other hand, if the inner peripheral surface of the switch-receiving space in the outer covering is outwardly displaced by thermal deformation, the gap between the horn switch button and the surrounding inner peripheral edge of the switch-receiving space or recess in the outer covering is increased or expanded to spoil the outer appearance of the steering wheel.